The traditional NH3 production
method (Haber–Bosch
process) is currently complemented by electrochemical synthesis at
ambient conditions, but the rather low selectivity (as indicated by
the Faradaic efficiency) for the electrochemical reduction of molecular
N2 into NH3 impedes the progress. Here, we present
a powerful method to significantly boost the Faradaic efficiency of
Au electrocatalysts to 67.8% for the nitrogen reduction reaction (NRR)
by increasing their electron density through the construction of inorganic
donor–acceptor couples of Ni and Au nanoparticles. The unique
role of the electron-rich Au centers in facilitating the fixation
and activation of N2 was also investigated via theoretical
simulation methods and then confirmed by experimental results. The
highly coupled Au and Ni nanoparticles supported on nitrogen-doped
carbon are stable for reuse and long-term performance of the NRR,
making the electrochemical process more sustainable for practical
application.
A crystalline microporous hydrogen-bonded cross-linked organic framework has been developed through covalent photo-cross-linking of molecular monomers that are assembled in a crystalline state. The elastic framework expands its void space to adsorb iodine rapidly with a high uptake capacity in an aqueous environment as well as recovering its crystalline form after the release of iodine.
Production of ammonia is currently realized by the Haber–Bosch process, while electrochemical N2 fixation under ambient conditions is recognized as a promising green substitution in the near future. A lack of efficient electrocatalysts remains the primary hurdle for the initiation of potential electrocatalytic synthesis of ammonia. For cheaper metals, such as copper, limited progress has been made to date. In this work, we boost the N2 reduction reaction catalytic activity of Cu nanoparticles, which originally exhibited negligible N2 reduction reaction activity, via a local electron depletion effect. The electron-deficient Cu nanoparticles are brought in a Schottky rectifying contact with a polyimide support which retards the hydrogen evolution reaction process in basic electrolytes and facilitates the electrochemical N2 reduction reaction process under ambient aqueous conditions. This strategy of inducing electron deficiency provides new insight into the rational design of inexpensive N2 reduction reaction catalysts with high selectivity and activity.
Integrating intelligent molecular systems into 3D printing materials and transforming their molecular functions to the macroscale with controlled superstructures will unleash great potential for the development of smart materials. Compared to macromolecular 3D printing materials, self-assembled small-molecule-based 3D printing materials are very rare owing to the difficulties of facilitating 3D printability as well as preserving their molecular functions macroscopically. Herein, we report a general approach for the integration of functional small molecules into 3D printing materials for direct ink writing through the introduction of a supramolecular template. A variety of inorganic and organic small-molecule-based inks were 3D-printed, and their superstructures were refined by post-printing hierarchical co-assembly. Through spatial and temporal control of individual molecular events from the nano- to the macroscale, fine-tuned macroscale features were successfully installed in the monoliths.
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